1. Technical Field
This disclosure relates to electric machines, and more specifically to synchronous motors and generators.
2. Related Art
Due to advances in form and performance demand for motors is increasing. Reduced sizes and improved reliability have broadened the acceptance of electric motors to industries that include transportation, aerospace, robotics, and healthcare.
Some motors use permanent magnets to generate torque. Because the properties of these materials may vary in time and the raw material costs may be excessive, such materials may be unsuitable for some applications. In vehicles, for example, fuel efficiency may be compromised when a permanent magnetic motor is not actuated to drive a vehicle. The continuous fields of the permanent magnets may resist the driving torque of a vehicle and generate core losses.